CVE-2021-47639: KVM: x86/mmu: Zap _all_ roots when unmapping gfn range in TDP MMU

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• linux linux kernel5.13 and later · before 5.15.33
• linux linux kernel5.16 and later · before 5.16.19
• linux linux kernel5.17 and later · before 5.17.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

• Linux Linux

  • 5.13affected
  • b7cccd397f310739fb85383033e95580f99927e0 and later · before af47248407c0c5ae52a752af1ab5ce5b0db91502affected · git
  • b7cccd397f310739fb85383033e95580f99927e0 and later · before 0c8a8da182d4333d9bbb9131d765145568c847b2affected · git
  • b7cccd397f310739fb85383033e95580f99927e0 and later · before 8cf6f98ab1d16d5e607635a0c21c4231eb15367eaffected · git
  • b7cccd397f310739fb85383033e95580f99927e0 and later · before d62007edf01f5c11f75d0f4b1e538fc52a5b1982affected · git
  • before 5.13not affected · semver
  • 5.15.33 and later · up to and including 5.15.*not affected · semver
  • 5.16.19 and later · up to and including 5.16.*not affected · semver
  • 5.17.2 and later · up to and including 5.17.*not affected · semver
  • 5.18 and laternot affected · original_commit_for_fix

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
  90Now
• CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
  89Now
• CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
  85Now

Published before and after this one in the same product

• ← EarlierCVE-2021-47637Feb 26, 2025 · ubifs: Fix deadlock in concurrent rename whiteout and inode writeback
  22Monitor
• ← EarlierCVE-2021-47638Feb 26, 2025 · ubifs: rename_whiteout: Fix double free for whiteout_ui->data
  22Monitor
• Later →CVE-2021-47640Feb 26, 2025 · powerpc/kasan: Fix early region not updated correctly
  31Monitor

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1free(dev->buf);2/* ... another thread is still running ... */3process(dev->buf);

1lock(&dev->lock);2free(dev->buf);3dev->buf = NULL;4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.